The invention relates to a device and a method for replacing lines without excavation, with the aid of an annular overdrilling head, which is moved over the line and is driven forward in the ground, and claims the priority of German patent application 100 65 532.7 to the content of which reference is made.
A device of the generic type is disclosed by DE 33 31 291 C2. This describes an open tubular drilling device which, for example, is placed on an underground cable and driven forward underground along the cable by the cutting force of high pressure nozzles. As a result, an annular space is produced around the cable, which facilitates or permits the removal of the cable from the ground. The device is guided by a drilling string and therefore not moved forward independently.
By contrast, DE 195 04 484 C1 discloses an open tubular drilling device which is driven through the ground by means of a linkage.
As a rule, devices of this type operate with a flushing device which comprises nozzles which are arranged on the head of the tubular forward drive element and to which flushing medium is applied.
Using the aforementioned devices, good results are achieved if no relatively large obstacles have to be overcome in the ground, rather the line to be freed is substantially free of branches, sockets or clips and, in the ground, no stones, fragments of pipe or capping stones have to be overcome.
In practice, however, the aforementioned obstacles are to be met frequently and constitute obstacles which cannot be overcome by the drilling devices described.
It is therefore an object of the invention to provide a drilling device and a drilling method which widens the field of use of known drilling devices and which is capable of overcoming specific obstacles present in the ground, which are virtually always to be expected.
The object of the invention is achieved by the subject matter of the independent claims. Advantageous refinements are the subject matter of the subclaims.